I think yhis song is obviously a sarcsstic view about the "that's the spirit" expressions, meaning that people who don't have depression and therefore don't understand it think it's easy to just "get out of it", so they say things like "that's the spirit!", "cheer up, dude" or in this case, "just simg along to a happy song". I remember seeing in an interview with Oli and the band saying that was the whole concept of the album, which I think is explicit in this song particularly. Also, the use of a "happy song" in general may be referring to Pharrel Williams "Happy", because people sing along to that happy song and pretend it's all ok, that the world has coalesced into one giant mess of hate and unrest.
I think yhis song is obviously a sarcsstic view about the "that's the spirit" expressions, meaning that people who don't have depression and therefore don't understand it think it's easy to just "get out of it", so they say things like "that's the spirit!", "cheer up, dude" or in this case, "just simg along to a happy song". I remember seeing in an interview with Oli and the band saying that was the whole concept of the album, which I think is explicit in this song particularly. Also, the use of a "happy song" in general may be referring to Pharrel Williams "Happy", because people sing along to that happy song and pretend it's all ok, that the world has coalesced into one giant mess of hate and unrest.